GB2377918A

GB2377918A - Chain wear measuring apparatus and method using two fixed sensors and two chain markers, and a control box with excessive chain elongation alarm

Info

Publication number: GB2377918A
Application number: GB0117993A
Authority: GB
Inventors: Paul M Shuffleton; James Lodovico Moruzzi
Original assignee: Renold PLC
Current assignee: Renold PLC
Priority date: 2001-07-24
Filing date: 2001-07-24
Publication date: 2003-01-29
Anticipated expiration: 2021-07-24
Also published as: GB2377918B; GB0501522D0; GB0117993D0; GB2406844A; GB2406843B; GB2406844B; GB0501521D0; GB2406843A

Abstract

A chain wear monitoring apparatus, suitable for monitoring elongation in a chain drive assembly, comprises first and second sensors S1, S2, mounted a fixed distance apart on a stationary support, and first and second markers M1 and M2 mounted, initially at a fixed and recorded distance apart, on the chain. A control unit 12 comprises a timer 15 which, triggered by electrical signals from the sensors S1, S2 generated as the chain markers M1, M2 pass the sensors S1,S2, measures the time elapsed between the signals generated for each of markers M1,M2 passing each of sensors S1, S2. From the signals generated the control unit processor 16 calculates the length of chain between the two markers M1,M2 and compares it to the original pre-measured length of the chain span which is stored a memory bank. Should any elongation in the chain exceed a pre-set threshold value, the control unit 12 sends a signal to activate an alarm, such as a visual 13 or audio 14 alarm to alert an operator of the apparatus. Also disclosed is an associated method and a kit of parts forming the apparatus. The system may incorporate magnets as the markers M1,M2 and Hall effect sensors S1,S2 or an optical / laser based system. The chain may feature further pairs of markers dividing the chain into a plurality of sections over each of which elongation may be measured separately. The control unit 12 may be configured to measure and display a variety of variables associated with chain motion, eg. velocity, average chain wear.

Description

CHAIN WEAR MONITORING APPARATUS AND METHOD The present invention relates to chain wear monitoring apparatus and an associated method.

Chain drive assemblies are used in many applications such as, for example, in conveyor systems used on manufacturing production lines, in transportation systems such as escalators, elevators or leisure rides (roller coasters etc. ), and in internal combustion engines for vehicles. In many applications multiple strands of chain will be used in a single drive assembly.

A chain drive assembly typically comprises at least one endless loop chain that passes around spaced wheels one of which is driven in rotation so as to circulate the chain and any components connected thereto. A chain typically comprises a plurality

of chain link assemblies that are interconnected by pins that pass through overlapping ing apertures in adjacent link assemblies.

Over a period of use, a chain will be subjected to wear by virtue of the rubbing friction between adjacent link assemblies and between the pins and the assemblies.

This wear results in elongation of the chain and eventually the chain will have to be replaced to avoid failure of the drive assembly. The rate of wear of a chain is dependent on the nature of the drive assembly in which it is fitted and the loads to which it is subjected. Failure cannot therefore be predicted with any certainty and regular visual inspection and/or manual measurement is required. This is obviously undesirable as it is labour intensive, imprecise and requires operation of the chain drive assembly to be temporarily interrupted.

US 5,490, 590 describes a chain wear monitor in which the length of a section of a chain is measured during regular operation of the chain drive system. The monitor comprises a wheel that is brought into frictional engagement with the chain. The wheel is mounted on a shaft that is connected to an encoder by a flexible coupling. The encoder translates rotational movement of the shaft into an electrical signal that is passed to a controller for processing. At the same time, the presence of each chain link is detected by a proximity sensor as it passes a predetermined location. The sensor generates a count signal that is passed to a controller for processing. The controller calculates from the distance and count signals a distance measurement per pre-

selected number of chain links. This arrangement has to be incorporated into the chain drive system and is prone to inaccuracies caused hy relative slip between the friction wheel and the chain.

It is an object of the present invention to obviate or mitigate the aforesaid

disadvantages and to provide for a method and apparatus for automatically monitoring Z7 the wear of a chain in-situ.

According to a first aspect of the present invention there i. s provided chain wear m nitoring apparatus for antomat. icahvmointormg the wear of a chain when in operation in a cham drive assembly, the apparatus comprising : hrst and second sensors mounted on a stationary support :"a predetermined fixed distance apart and for gencra'nng electrical signals in response t0 the detection of :.'t ! eas*. h-s* a d second markers assoe. ated \\. th'. he chain, me markers herni dispo ed mitiahv at a predctcrmined distance apart ; a contnd unit connected to said sensors so as to rcceive said si nals theiefrom : tie contro) unit compnsmg a tuner that is triggered lpon receipt ofsaid signals horn said sensors so as to measure the elapsed'mie between rece ! pt of signals from die sensors ; at Li I-) to f-cce S"i iiiilt cc) [111. cici to the control unit being configured to measure a first ekipsed time value between L7 tc) si, 7, 1, 1lls signals generated by one of the markers passing between first and second sensors and one of, tilf to determine me speed of travcl of the chain from die lirst elapsed tune vaiuc and the of the iied d'StLITIC-tl) c vatue of the predetermined distance betwcen the sensors : the contro1 unit also bemg cont12urcd sn as to meJSllr (' a second elapsed time value between signals generated bv the first marker passing one of said sensors and the second marker passing one of said sensors, the control unit ncorporating means for calculating the distance between the markers from the determined speed of travel of the chain and the first and second

I I I incy elapsed time values, means for calculating the elongation of the chain by deducting the predetermined distance between the markers from the calculated distance between the markers, and means for comparing the calculated elongation with a predetermined threshold value ; and

an alarm signal generator connected to the control unit and for issuing an alarm signal if the calculated elongation exceeds said threshold value.

The invention allows the wear of a chain to be monitored automatically in real time without interruption of the operation of the chain drive assembly and without the need to remove the chain from the drive assembly. It can be used to predict or determine when a particular chain will require replacement and to assist in the diagnosis of faults in a chain drive assembly. Furthermore the apparatus can be used to determine the relative elongation and wear of different sections in a single chain.

The alarm signal may be visual or audible.

Where two or more parallel chains are used in the drive assembly the apparatus can be used to compare the wear of the chains.

Preferably the control unit comprises means for calculating the rate of wear of the chain over a period of use.

The apparatus may further comprise a visual display for displaying the calculated chain velocity, length, rate of wear and/or the presence of alarm signals.

Preferably the calculated elongation is compared with two predetermined thresholds representing different values of chain elongation and the alarm signal generator is designed to issue first and second alarm signals.

The apparatus may have two or more sets of first and second sensors for monitoring wear in two or more chains each having at least two markers-The control unit comprises means for comparing the calculated values of chain elongation and to generate a signal to trigger the alarm signal generator if the difference between the values exceeds a predetermined threshold value Preferably the markers are designed to fit directly or indirectly to the, or each, chain.

In one preferred embodiment the distance between the sensors is equal to the initial predetermined distance between markers and therefore the second elapsed time value is that between signals generated by the first marker passing the first sensor and the second marker passing the second sensor.

The sensors are preferably inductive or Hall-effect type, although other types may be used.

The control unit may he configured to monitor chain wear at different sections along a chain by using more than two markers, means being provided to calculate the chain elongation at each of the different sections along chain. The control unit mav comprise a comparator for comparing the calculated values of chain elongation at each of the different sections along me chain and may generate a signal to trigger the alarm signal generator if one section of the chain is wearing more rapidiv than another.

The control unit mav al o comprisc means for calculating tle average wear of the chain from the calculated values of chain elongation.

According to a s cond aspect of the present, invention there is pro\ided a method for antomaucaiiy monitoring tlie wear of a chain when in operation in a chain drive assembly, using tn'st and second sensors disposed at a predetermined fixed (i i St ilil C t T l t r T (t l l (l''l t i l l e c t X] s i. < s l !' !-C e't,-) T} t fz c t distlnce apart and ir 'c'nlr.' irj, e ! ectric i signals m r s'''o'ise to the deiecb ;' ;. p. :' least first and second markers associated with the cliam. the markers hem"disposed '. nitiath at a predeter ined di. o. a ce apart, and using a eoni olumt c rupnsimj. a'ime ; '. hat is trigger d upon reccip'. one et'said sign ls from one of the sensors so as to measure the elapsed time between ieceipt of signals trnm the sensors, the uiemod comprising the steps of, measuring a Hrst elapsed'. ime value between signals eenerated bv one of the markers passing between first and second sensors, tile StCL) s (f LCllc]-Litci I-) %, olit of til, l determining the speed at travel of the chain from'he elapsed tine value and oftlie t, lie b f7 the value of the predetermined dis'ance between the sensors : measuring a second clapsed time value between slgnals generated bv the first marker passing one of said sensors and the second marker passing one of the sensors : calculating the distance between the markers from the speed of travel and the first and second elapsed [ime values : calculating the elongation of the chain by deducting the predetermined distance between the markers from the calculated distance between the markers ; comparing the calculated elongation with a predetermined threshold value ; and generating an alarm signal if the calculated elongation exceeds said threshold value.

According to a third aspect of the present invention there is provided a kit of parts for automatically monitoring the wear of a chain when in operation in a chain drive assembly, the apparatus comprising : first and second markers for connection directly or indirectly to the chain; first and second sensors mounted on a stationary support at a predetermined fixed distance apart and for generating electrical signals in response to the detection of

'd f 1 0 said first and second markers, the markers, in use, being disposed initially at a s predetermined distance apart; a control unit connected to said sensors so as to receive said signals therefrom ; the control unit comprising a timer that is triggered upon receipt of said signals from said sensors so as to measure the elapsed time between receipt of signals from the sensors; the control unit being configured to measure a first elapsed time value between signals generated by one of the markers passing between first and second sensors and to determine the speed of travel of the chain from the elapsed time value and the value of the predetermined distance between the sensors; the control unit also being configured so as to measure a second elapsed time value between signals generated by the first marker passing one of said sensors and the second marker passing one of the sensors;

the control unit incorporating means for calculating the distance between the I Z-1 markers from the determined speed of travel of the chain and the first and second elapsed time values, means for calculating the elongation of the chain by deducting the predetermined distance between the markers from the calculated distance between the markers, and means for comparing the calculated elongation with a predetermined threshold value; and an alarm signal generator for issuing an alarm signal if the calculated elongation exceeds said threshold value.

A specific embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

figure 1 is a schematic representation of the chain wear monitoring apparatus and the chain of a chain drive assembly shown at three different points in time during its travel.

The exemplary chain wear monitoring apparatus comprises a pair of inductive

or Hall-effect sensors St. S. disposed near to the chain 1 at a fixed distance L apart on a stationary support structure H such as. for example, a framework that cames the chain drive assembly. The sensors S ;. S. ; are connected to a control unit 12 that rccci\cs and pruccsses the sl : :'Jla s t 'o1l the sc'nsors S. S, and generates output si that drive a visua) dispiav 13 and an alarm unit) 4. ttici an Lilii-iii tiiilt 14. the control ult] 2 complses conventiona ipnal conditioning circuit ; \. a timer 15. a processor tb with associatel memon. and an output circint for driv'm'. me s-l el ; er) t f ) he chain M of the chain dnve a. ssemhi\ ; s in the form (nan endless toon thai passes around at ieasi a pan'of wheels (no',.-. hown). one o ;'\\iueb drives'. he chau : A section of the chain ! < ; is represented in ngure i and i. : fno\\n as travehme in Lhe direc'oon trom ! e ! t [o m'. n !.

The chainl')'. ti'. ted \\'nh two u'arkers M. M. diat are composed ol'a direc ! iull l 'om kil [ ;II ri niatenal to \vhich the sensors are sensitive (e. g. magnetic dements) and ane disposed inmabv al a predetermined distance apart t ..'the markers \b. M ; mav simpl \' chn or at-i otherwise fasten directiv or indirectiv on to the cham, Before operation of the chain wear monitor the control unit 12 is pre@

rogrammedwith thevaluesof distanceL.th initia distance L between the markers, a first threshold w ar ength f. and au ultim te threshold wear lcngth. I... : i ! the vaincs being stored in the processor memorv.

When the chain dri\e assembly is in operation the chain circulates around the wdeels and passes the sensors S S, from left to right in the view shown in figure !. As each marker \1" \1 ; passes in front of a sensor an electrical signal is generated and passed to the control unit 12.

As marker M ; passes sensor S) the control unit 12 starts the timer 15 in

response to the signal received. This is represented in figure I by the diagram labelled I as t=0. When marker M, then passes sensor S2 the time elapsed in travelling the

distance LI is recorded as tu. Shortly after marker M2 passes sensor S, and the time elapsed in travelling the distance L2 is recorded as tL2.

The elongation of the chain is then calculated from the recorded elapsed time

values tu and tL2 and the pre-programmed values of LI and L2. The elongation of the chain is calculated as:

Where Lj/tu is the velocity of the chain and is recorded separately by the control unit for information purposes.

The processor 16 continually compares the present calculated elongation Lw of the chain with the first wear length threshold La and when it exceeds the threshold a signal is generated to sound a first alarm signal. Similarly, a comparison is made with the ultimate wear length threshold Lu and when it is exceeded the control unit will generate a second signal to sound a second alarm.

The display continually provides a reading of the current chain velocity, current chain elongation length Lw and the rate of elongation (rate of wear).

The apparatus can be used to monitor the wear of two chains that are running in parallel to drive a conveyor such as, for example, an escalator. In such an application each chain has at least two markers and a pair of sensors mounted in proximity thereto. The control unit receives signals from both sensors and is preprogrammed with the parameters relating to each chain. The chain wear is monitored in both chains by the control unit. The difference between the two calculated elongation values is determined and compared to a predetermined threshold value Ld. If this value is exceeded the control unit issues a signal to the alarm signal generator and an appropriate alarm is sounded. This is particularly important in conveyors such as escalators as inequality of wear of the two chains may result in damage to the chain drive assembly or the escalator itself.

The initial distance between the markers L2 may be set at a value greater than, less than or equal to the distance between the sensors Ll. If the distances LI and L2 are arranged to be equal when the chain is new, the sensors Si, S2 will initially generate signals simultaneously and as the chain wears the signal generated by the passage of

the second marker M2 past the first sensor S, will ag that generated by the first M, marker passing the second sensor S,, It \vil) he appreciated that numerous modifications to the above described design may he made without departing from the scope of the invention as defined in the appended claims. For example, the chain may be fitted with more than two markers and the chain elongation measured for different sections of the chain. An ,verage chain wear ma\'he calcuiated by the control mnt from the measured vahaes.

Moreover, if a comparison) S made of the calculated elongation vahjls this metlod enables identification of a section of chain that. is wearing at a greater rate than other sections. Furtlelmore, the sensors may be of any suitable type for d tee'"' ! g the presence of a marker e. g. optica] or ! aser based. o) 1,. CLII ol-

Claims

CLAIMS 1. Chain wear monitoring apparatus for automatically monitoring the wear of a chain when in operation in a chain drive assembly, the apparatus comprising: first and second sensors mounted on a stationary support at a predetermined fixed distance apart and for generating electrical signals in response to the detection of at least first and second markers associated with the chain, the markers being disposed initially at a predetermined distance apart; a control unit connected to said sensors so as to receive said signals therefrom ; the control unit comprising a timer that is triggered upon receipt of said signals from said sensors so as to measure the elapsed time between receipt of signals from the sensors; the control unit being configured to measure a first elapsed time value between signals generated by one of the markers passing between first and second sensors and to determine the speed of travel of the chain from the first elapsed time value and the value of the predetermined distance between the sensors; the control unit also being configured so as to measure a second elapsed time value between signals generated by the first marker passing one of said sensors and the second marker passing one of the sensors ; the control unit incorporating means for calculating the distance between the markers from the determined speed of travel of the chain and the first and second elapsed time values, means for calculating the elongation of the chain by deducting the predetermined distance between the markers from the calculated distance between the markers, and means for comparing the calculated elongation with a predetermined threshold value; and an alarm signal generator connected to the control unit and for issuing an alarm signal if the calculated elongation exceeds said threshold value.

2. Chain wear monitoring apparatus according to claim 1, wherein the alarm signal is visual and/or audible.

3. Chain wear monitoring apparatus according to claim 1 or 2, wherein two or more parallel chains are used in the drive assembly, the means for calculating the

<Desc/Clms Page number 10>

elongation of the chains is configured to perform said catenation for each chain and the control unit comprises a comparator for comparing the elongation of each chain over time.

4 Chain wear monitoring apparatus according to cJaim I. 2 or. \ wherein tle control unit comprises means for calculating the rate of wear of the chain (or chains) over a period of use. to 11-ic . Chain \\'ear monn r g apparatls according to anv precedi g ) lim. tnrt'er comprising a \' ! sna) disp ! a\'connected to the contndanha'i. d to ; disp) : i\meth. e caicn ! atedcl'iam\elocn\'. length, rate ot\\ear and or th. c presence of ataimsnma ! s n (nani \\ear mom'ormganparat'as according to an\'preccdmL'chum. \\tierem means tor coi'iiparnig. the ai aiat deiongatioriconKiar- die calculated \'a ; L ! e\\'iih t\\o pre etermined i iire. icids representing diiferen ! \a ! uc.l)l'chain e) onc ! ion illellis II () I- ". Cham \vear moniKring apparatus according to an\ preceduie clann. further c mprising t\vo or more ets cf first and second sensors ; (r nioi : tormo : \vear ; n t\\'o or more ehams each ha\'mg at] east f'o markers.

8. ('ham wear monnonnc apparatus acc rding to clail". \\'hereut the contn'i nnit comprises means for companngthe ca ! cu) ated \'a ! ues o ;'cham etnnation for each chain and means to generate, a signal to tngger the atann siia ! generator if the difference between the chain elongation \'a) nes exceeds a predeten-nined threshold \'ahie. a] ue 9. Chain wear monitoring apparatus according to any preceding claim, wherein the distance between the sensors is equal to the initial prcdele1l11ined distance between markers and the second elapsed time value is between signals generated by the

<Desc/Clms Page number 11>

first marker passing said first sensor and by the second marker passing the second sensor.

10. Chain wear monitoring apparatus according to any preceding claim, wherein the sensors are inductive or Hall-effect type.

11. Chain wear monitoring apparatus according to any preceding claim, wherein the control unit is configured to monitor chain wear at different sections along a chain

by using more than two markers, means being provided to calculate the chain I LD elongation at each of the different sections along the chain.

12-Chain wear monitoring apparatus according to claim 11, wherein the control unit comprises a comparator for comparing the calculated values of chain elongation at each of the different sections along the chain and means for generating a signal to

trigger the alarm signal generator if one section of the chain is wearing more trigger t rapidly than another.

13. Chain wear monitoring apparatus according to claim 1 or 12, wherein the control unit comprises means for calculating the average wear of the chain from the calculated values of chain elongation.

14. A method for automatically monitoring the wear of a chain when in operation in a chain drive assembly, using first and second sensors disposed at a predetermined fixed distance apart and for generating electrical signals in response to the detection of at least first and second markers associated with the chain, the markers being disposed initially at a predetermined distance apart, and using a control unit comprising a timer that is triggered upon receipt one of said signals from one of the sensors so as to measure the elapsed time between receipt of signals from the sensors ; the method comprising the steps of : measuring a first elapsed time value between signals generated by one of the markers passing between first and second sensors; determining the speed of travel of the chain

<Desc/Clms Page number 12>

from the first elapsed time value and the value of the predetermined distance between the sensors measuring a second elapsed time value between signals generated by the first marker passing one of said sensors and the second marker passing one of said sensors, calculating the distance between the markers from the speed of travel and tht first and second elapsed time values calculating the elongation of the chain by deducting the predetermined distance bet\veen tlie markers from die calculated distance between the markers, comparing the calculated elon ation \Mth a prcdetermined threshold vainer and generatm' ;' an 7 larm ignalit'm ca cukited elongation exceeds said nireshold value.

1 : \ method according m chum ! 4. \vherem t\'-o or more paralte chains arl ned m

III. I il-I 1-1,, 1,--.,,,, ', !. . I' ! t .,, ! 1--,

ea h of the chains and coropnrin the ek'rgati n of each chai ver tune. i I I c Lilill I t l I , T" : i) Lh ra' cc ! f\\' arot'. hc. ! mn (i' :'c..'. ! !'ooe\'ra :''e''h''d'nse. ic-coF (ii"l -T tO OTI (' dis ! a\'mg the ca ! cuiatedchtainveiocitvicngth. rate ot wear and or t !') o presence 0 ; atarTusinats.

IS. Amef ! in (iacc (irdinloart (inc () !'cIainr'. tto]". furthercor'riprisit') [hestepo !' compan the cak-Lalcd clona'ori vaiucwith two predetermined thresholds represen'. ing dtilcrcrlt \'a ! ucs of chain ciongation and issuing first and or second alarm signals n'the respective chatrt clongation values arc exceeded. t9. A method according to any one of claim 14 to IS, wherein two or more sets of first and second sensors are used to monitor wear in two or more chains, each of the chains having at ieast two markers.

<Desc/Clms Page number 13>

20. A method according to claim 19, further comprising the steps of comparing the calculated values of chain elongation for each chain and generating a signal to

trigger an alarm signal if the difference between the values exceeds a c predetermined threshold value.

21. A method according any one of claims 14 to 20, further comprising the step of monitoring the chain wear at different sections along a chain by using more than two markers, and calculating the chain elongation at each of the different sections along the chain.

22. A method according to claim 21, further comprising the step of comparing the calculated values of chain elongation at each of the different sections along the chain and issuing an alarm signal if one section of the chain is wearing more rapidly than another.

23. A method according to claim 21 or 22, further comprising the step of calculating the average wear of the chain from the calculated values of chain elongation.

24. A kit of parts for automatically monitoring the wear of a chain when in operation in a chain drive assembly, the apparatus comprising : first and second markers for connection directly or indirectly to the chain ; first and second sensors mounted on a stationary support at a predetermined fixed distance apart and for generating electrical signals in response to the detection of said first and second markers, the markers, in use, being disposed initially at a predetermined distance apart; a control unit connected to said sensors so as to receive said signals therefrom; the control unit comprising a timer that is triggered upon receipt of said signals from said sensors so as to measure the elapsed time between receipt of signals from the sensors ; the control unit being configured to measure a first elapsed time value between signals generated by one of the markers passing between first and second sensors and to determine the speed of travel of the chain from the first elapsed time value and the value of the predetermined distance between the sensors; the

<Desc/Clms Page number 14>

control unit also being configured so as to measure a second elapsed time value between signals generated by the first, marker passing one of said sensors and the second marker passing one of said sensors ; the control unit incorporating means I I for calculating the distance between the markers from the determined speed of travel of the chain and the first and second etapscd time values, mcan. s for calculating the elongation of the chain bv deducting the predetermined distance between the markers from the calculated distance between the markers, and means 'or comparing the cremated elongation With a predetermined threshotd value : and a)) alarm signa ! generator for tssumg an alarm signa] if'he eaicmated eb'neadon L'. \CL'eds said'direshold \atUL'.

25. (ham welr monnorniL'a ;') :') ar tus l'i an'i : tillal horr-mbeforr'Jr'"-',''t'r) :/. j l\nf : reterence to die accompanying drawmgs ol-C"Iictll (, Ite (i nereUibeiore descnnei.} \\ :'Lii re ! ei\' ; . \'' w f ;'ie ace'moan'. mL' dr : i\\". n :.'s ls Su iilr < > sl ri lel e ne e lo vlae el (C011ll) Lll di a\ lilt s